Polyorganosiloxanes having organic functional groups are used widely, for example as modifiers for organic resins, surfactants or fiber-treating agents. The chemical structures of such polyorganosiloxanes depend on the kinds, numbers and positions of the organic functional groups, and so on, and are selected properly according to uses. Particularly, to modify organic resins by incorporating polyorganosiloxanes into the molecules of the organic resins by copolymerization, organic functional groups copolymerizable with the organic resins should be chosen, and the number and positions thereof should also be adjusted precisely. Some of such polyorganosiloxanes have organic functional groups at both ends of the molecule chain, and some have an organic functional group at only one end of the molecule chain. The former having organic functional groups at both ends of the molecule chain are used to modify organic resins produced mainly by condensation polymerization, such as polyester resins, polyamide resins, polycarbonate resins and polysulfones. Such polyorganosiloxanes involve the problem that the copolymerization thereof with organic resin monomers cannot give graft copolymers having polyorganosiloxane chains branching from the molecular chain of the organic resins. The latter having one organic functional group at one end of the molecule chain also involve the problems that when copolymerized in the same manner, they cannot improve the properties of the resulting organic resins sufficiently.
To solve these problems, polyorganosiloxanes having two or more organic functional groups at one end of the molecule chain were proposed (Japanese Patent Application Unexamined Publication No. 4-323222 (1992)), but are inapplicable to modify polycarbonates and polysulfones because their organic functional groups are limited to amino, carboxyl, hydroxyl and epoxy.
Polycarbonate resins, being excellent in heat resistance and impact resistance, have been used extensively. They, however, are poor in moldability, releasability and water repellence. So, there are proposed the addition of additives, such as plasticizers and release agents, and copolymerization with polyorganosiloxanes having the above-described organic functional groups. The latter technique gives, for example, polycarbonate resins containing siloxane units in the main chain (Japanese Patent Application Unexamined Publication No. 3-79626 (1991)), and polycarbonate resins wherein siloxane chains are grafted to improve the free rotation of polyorganosiloxane chains (Japanese Patent Application Unexamined Publication Nos. 5-155999 (1993) and 7-165897 (1995)). Even in the latter polycarbonate resins, the free rotation of polyorganosiloxane chains are not enough to sufficiently improve the surface properties including moldability, releasability and water repellence.
In electrophotographic photoreceptor industries, the conventional inorganic photoreceptors used in copying machines, printers and facsimiles are being replaced by organic electrophotographic photoreceptors (OPC) which are superior in non-environmental pollution, productivity and the possibility of various modifications. Even in high-speed and highly durable machines, wherein inorganic photoreceptors have been unrivaled, there is a movement toward the use of organic electrophotographic photoreceptors. This movement, however, is retarded because the conventional organic electrophotographic photoreceptors are inferior to inorganic photoreceptors in durability and cause severe toner-filming, which is a defect in printed images caused by foreign matter (toner, paper powder, external additives, etc.) adhering to photoreceptors.
Our studies in the cause of the filming revealed that the filming is triggered by the weak adhesion of foreign matter to photoreceptors with intermolecular forces, and can be prevented effectively by photoreceptors of weak adhesion (intermolecular force) to foreign matter, particularly photoreceptors having a surface layer containing at least as resin ingredients copolymers of polysiloxanes with polycarbonates.
There have been proposed some electrophotographic photoreceptors produced by using copolymers of polysiloxanes with polycarbonates (e.g. Japanese Patent Application Unexamined Publication Nos. 61-132954 (1986) and 2-240655 (1990)). These copolymers however have poor compatibility with charge-transfer substances, and the coating fluid whitened or set to gel half a day to a few days after the preparation. To prevent the whitening and gelation, there were proposed copolymers of polycarbonates and polysiloxanes both ends of which are modified with phenol (Japanese Patent Application Unexamined Publication Nos. 5-72753 (1993) and 5-297620 (1993)), and terpolymers produced by incorporating specific bisphenol structures into polycarbonates of polysiloxanes both ends of which are modified with phenol (Japanese Patent Application Unexamined Publication No. 6-220181 (1994)). The improvement in the compatibility of the former copolymers with charge-transfer substances is insufficient, and the whitening or gelation of coating fluid occurs a few days to a month after the preparation. Even coating fluid yet to set to gel is suffered by the micro-phase-separation of charge-transfer substances and binder resins, and when used to produce photoreceptors, causes deterioration in the electric properties of the product photoreceptors, such as low sensitivity (half-value exposure) and increased residual potential. Though the latter terpolymers are so improved in compatibility with charge-transfer substances by the copolymerization of the specific third ingredient as to stabilize coating fluid for several months or more, the essential third ingredient restricts the control of the properties of the polycarbonates, and the reproduction of the same polymer is difficult because it is difficult to control the reactions of the three kinds of monomers evenly.